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Break SCEVExpander out of IndVarSimplify into its own .h/.cpp file so that

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other passes may use it.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22557 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nate Begeman 2005-07-30 00:12:19 +00:00
parent 01546c5d50
commit 36f891bdf6
3 changed files with 286 additions and 238 deletions
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180
include/llvm/Analysis/ScalarEvolutionExpander.h Normal file
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//===---- llvm/Analysis/ScalarEvolutionExpander.h - SCEV Exprs --*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the classes used to generate code from scalar expressions.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ANALYSIS_SCALAREVOLUTION_EXPANDER_H
#define LLVM_ANALYSIS_SCALAREVOLUTION_EXPANDER_H
#include "llvm/BasicBlock.h"
#include "llvm/Constants.h"
#include "llvm/Instructions.h"
#include "llvm/Type.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Analysis/ScalarEvolutionExpressions.h"
#include "llvm/Support/CFG.h"
namespace llvm {
/// SCEVExpander - This class uses information about analyze scalars to
/// rewrite expressions in canonical form.
///
/// Clients should create an instance of this class when rewriting is needed,
/// and destroying it when finished to allow the release of the associated
/// memory.
struct SCEVExpander : public SCEVVisitor<SCEVExpander, Value*> {
ScalarEvolution &SE;
LoopInfo &LI;
std::map<SCEVHandle, Value*> InsertedExpressions;
std::set<Instruction*> InsertedInstructions;
Instruction *InsertPt;
friend struct SCEVVisitor<SCEVExpander, Value*>;
public:
SCEVExpander(ScalarEvolution &se, LoopInfo &li) : SE(se), LI(li) {}
/// clear - Erase the contents of the InsertedExpressions map so that users
/// trying to expand the same expression into multiple BasicBlocks or
/// different places within the same BasicBlock can do so.
void clear() { InsertedExpressions.clear(); }
/// isInsertedInstruction - Return true if the specified instruction was
/// inserted by the code rewriter. If so, the client should not modify the
/// instruction.
bool isInsertedInstruction(Instruction *I) const {
return InsertedInstructions.count(I);
}
/// getOrInsertCanonicalInductionVariable - This method returns the
/// canonical induction variable of the specified type for the specified
/// loop (inserting one if there is none). A canonical induction variable
/// starts at zero and steps by one on each iteration.
Value *getOrInsertCanonicalInductionVariable(const Loop *L, const Type *Ty){
assert((Ty->isInteger() || Ty->isFloatingPoint()) &&
"Can only insert integer or floating point induction variables!");
SCEVHandle H = SCEVAddRecExpr::get(SCEVUnknown::getIntegerSCEV(0, Ty),
SCEVUnknown::getIntegerSCEV(1, Ty), L);
return expand(H);
}
/// addInsertedValue - Remember the specified instruction as being the
/// canonical form for the specified SCEV.
void addInsertedValue(Instruction *I, SCEV *S) {
InsertedExpressions[S] = (Value*)I;
InsertedInstructions.insert(I);
}
/// expandCodeFor - Insert code to directly compute the specified SCEV
/// expression into the program. The inserted code is inserted into the
/// specified block.
///
/// If a particular value sign is required, a type may be specified for the
/// result.
Value *expandCodeFor(SCEVHandle SH, Instruction *IP, const Type *Ty = 0) {
// Expand the code for this SCEV.
this->InsertPt = IP;
return expandInTy(SH, Ty);
}
protected:
Value *expand(SCEV *S) {
// Check to see if we already expanded this.
std::map<SCEVHandle, Value*>::iterator I = InsertedExpressions.find(S);
if (I != InsertedExpressions.end())
return I->second;
Value *V = visit(S);
InsertedExpressions[S] = V;
return V;
}
Value *expandInTy(SCEV *S, const Type *Ty) {
Value *V = expand(S);
if (Ty && V->getType() != Ty) {
// FIXME: keep track of the cast instruction.
if (Constant *C = dyn_cast<Constant>(V))
return ConstantExpr::getCast(C, Ty);
else if (Instruction *I = dyn_cast<Instruction>(V)) {
// Check to see if there is already a cast. If there is, use it.
for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
UI != E; ++UI) {
if ((*UI)->getType() == Ty)
if (CastInst *CI = dyn_cast<CastInst>(cast<Instruction>(*UI))) {
BasicBlock::iterator It = I; ++It;
if (isa<InvokeInst>(I))
It = cast<InvokeInst>(I)->getNormalDest()->begin();
while (isa<PHINode>(It)) ++It;
if (It != BasicBlock::iterator(CI)) {
// Splice the cast immediately after the operand in question.
BasicBlock::InstListType &InstList =
It->getParent()->getInstList();
InstList.splice(It, CI->getParent()->getInstList(), CI);
}
return CI;
}
}
BasicBlock::iterator IP = I; ++IP;
if (InvokeInst *II = dyn_cast<InvokeInst>(I))
IP = II->getNormalDest()->begin();
while (isa<PHINode>(IP)) ++IP;
return new CastInst(V, Ty, V->getName(), IP);
} else {
// FIXME: check to see if there is already a cast!
return new CastInst(V, Ty, V->getName(), InsertPt);
}
}
return V;
}
Value *visitConstant(SCEVConstant *S) {
return S->getValue();
}
Value *visitTruncateExpr(SCEVTruncateExpr *S) {
Value *V = expand(S->getOperand());
return new CastInst(V, S->getType(), "tmp.", InsertPt);
}
Value *visitZeroExtendExpr(SCEVZeroExtendExpr *S) {
Value *V = expandInTy(S->getOperand(),S->getType()->getUnsignedVersion());
return new CastInst(V, S->getType(), "tmp.", InsertPt);
}
Value *visitAddExpr(SCEVAddExpr *S) {
const Type *Ty = S->getType();
Value *V = expandInTy(S->getOperand(S->getNumOperands()-1), Ty);
// Emit a bunch of add instructions
for (int i = S->getNumOperands()-2; i >= 0; --i)
V = BinaryOperator::createAdd(V, expandInTy(S->getOperand(i), Ty),
"tmp.", InsertPt);
return V;
}
Value *visitMulExpr(SCEVMulExpr *S);
Value *visitUDivExpr(SCEVUDivExpr *S) {
const Type *Ty = S->getType();
Value *LHS = expandInTy(S->getLHS(), Ty);
Value *RHS = expandInTy(S->getRHS(), Ty);
return BinaryOperator::createDiv(LHS, RHS, "tmp.", InsertPt);
}
Value *visitAddRecExpr(SCEVAddRecExpr *S);
Value *visitUnknown(SCEVUnknown *S) {
return S->getValue();
}
};
}
#endif

105
lib/Analysis/ScalarEvolutionExpander.cpp Normal file
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//===- ScalarEvolutionExpander.cpp - Scalar Evolution Analysis --*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains the implementation of the scalar evolution expander,
// which is used to generate the code corresponding to a given scalar evolution
// expression.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/ScalarEvolutionExpander.h"
using namespace llvm;
Value *SCEVExpander::visitMulExpr(SCEVMulExpr *S) {
const Type *Ty = S->getType();
int FirstOp = 0; // Set if we should emit a subtract.
if (SCEVConstant *SC = dyn_cast<SCEVConstant>(S->getOperand(0)))
if (SC->getValue()->isAllOnesValue())
FirstOp = 1;
int i = S->getNumOperands()-2;
Value *V = expandInTy(S->getOperand(i+1), Ty);
// Emit a bunch of multiply instructions
for (; i >= FirstOp; --i)
V = BinaryOperator::createMul(V, expandInTy(S->getOperand(i), Ty),
"tmp.", InsertPt);
// -1 * ... ---> 0 - ...
if (FirstOp == 1)
V = BinaryOperator::createNeg(V, "tmp.", InsertPt);
return V;
}
Value *SCEVExpander::visitAddRecExpr(SCEVAddRecExpr *S) {
const Type *Ty = S->getType();
const Loop *L = S->getLoop();
// We cannot yet do fp recurrences, e.g. the xform of {X,+,F} --> X+{0,+,F}
assert(Ty->isIntegral() && "Cannot expand fp recurrences yet!");
// {X,+,F} --> X + {0,+,F}
if (!isa<SCEVConstant>(S->getStart()) ||
!cast<SCEVConstant>(S->getStart())->getValue()->isNullValue()) {
Value *Start = expandInTy(S->getStart(), Ty);
std::vector<SCEVHandle> NewOps(S->op_begin(), S->op_end());
NewOps[0] = SCEVUnknown::getIntegerSCEV(0, Ty);
Value *Rest = expandInTy(SCEVAddRecExpr::get(NewOps, L), Ty);
// FIXME: look for an existing add to use.
return BinaryOperator::createAdd(Rest, Start, "tmp.", InsertPt);
}
// {0,+,1} --> Insert a canonical induction variable into the loop!
if (S->getNumOperands() == 2 &&
S->getOperand(1) == SCEVUnknown::getIntegerSCEV(1, Ty)) {
// Create and insert the PHI node for the induction variable in the
// specified loop.
BasicBlock *Header = L->getHeader();
PHINode *PN = new PHINode(Ty, "indvar", Header->begin());
PN->addIncoming(Constant::getNullValue(Ty), L->getLoopPreheader());
pred_iterator HPI = pred_begin(Header);
assert(HPI != pred_end(Header) && "Loop with zero preds???");
if (!L->contains(*HPI)) ++HPI;
assert(HPI != pred_end(Header) && L->contains(*HPI) &&
"No backedge in loop?");
// Insert a unit add instruction right before the terminator corresponding
// to the back-edge.
Constant *One = Ty->isFloatingPoint() ? (Constant*)ConstantFP::get(Ty, 1.0)
: ConstantInt::get(Ty, 1);
Instruction *Add = BinaryOperator::createAdd(PN, One, "indvar.next",
(*HPI)->getTerminator());
pred_iterator PI = pred_begin(Header);
if (*PI == L->getLoopPreheader())
++PI;
PN->addIncoming(Add, *PI);
return PN;
}
// Get the canonical induction variable I for this loop.
Value *I = getOrInsertCanonicalInductionVariable(L, Ty);
if (S->getNumOperands() == 2) { // {0,+,F} --> i*F
Value *F = expandInTy(S->getOperand(1), Ty);
return BinaryOperator::createMul(I, F, "tmp.", InsertPt);
}
// If this is a chain of recurrences, turn it into a closed form, using the
// folders, then expandCodeFor the closed form. This allows the folders to
// simplify the expression without having to build a bunch of special code
// into this folder.
SCEVHandle IH = SCEVUnknown::get(I); // Get I as a "symbolic" SCEV.
SCEVHandle V = S->evaluateAtIteration(IH);
//std::cerr << "Evaluated: " << *this << "\n to: " << *V << "\n";
return expandInTy(V, Ty);
}

239
lib/Transforms/Scalar/IndVarSimplify.cpp
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@ -42,7 +42,7 @@
#include "llvm/Constants.h"
#include "llvm/Instructions.h"
#include "llvm/Type.h"
#include "llvm/Analysis/ScalarEvolutionExpressions.h"
#include "llvm/Analysis/ScalarEvolutionExpander.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Support/CFG.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
@ -51,243 +51,6 @@
#include "llvm/ADT/Statistic.h"
using namespace llvm;
namespace {
/// SCEVExpander - This class uses information about analyze scalars to
/// rewrite expressions in canonical form.
///
/// Clients should create an instance of this class when rewriting is needed,
/// and destroying it when finished to allow the release of the associated
/// memory.
struct SCEVExpander : public SCEVVisitor<SCEVExpander, Value*> {
ScalarEvolution &SE;
LoopInfo &LI;
std::map<SCEVHandle, Value*> InsertedExpressions;
std::set<Instruction*> InsertedInstructions;
Instruction *InsertPt;
friend struct SCEVVisitor<SCEVExpander, Value*>;
public:
SCEVExpander(ScalarEvolution &se, LoopInfo &li) : SE(se), LI(li) {}
/// isInsertedInstruction - Return true if the specified instruction was
/// inserted by the code rewriter. If so, the client should not modify the
/// instruction.
bool isInsertedInstruction(Instruction *I) const {
return InsertedInstructions.count(I);
}
/// getOrInsertCanonicalInductionVariable - This method returns the
/// canonical induction variable of the specified type for the specified
/// loop (inserting one if there is none). A canonical induction variable
/// starts at zero and steps by one on each iteration.
Value *getOrInsertCanonicalInductionVariable(const Loop *L, const Type *Ty){
assert((Ty->isInteger() || Ty->isFloatingPoint()) &&
"Can only insert integer or floating point induction variables!");
SCEVHandle H = SCEVAddRecExpr::get(SCEVUnknown::getIntegerSCEV(0, Ty),
SCEVUnknown::getIntegerSCEV(1, Ty), L);
return expand(H);
}
/// addInsertedValue - Remember the specified instruction as being the
/// canonical form for the specified SCEV.
void addInsertedValue(Instruction *I, SCEV *S) {
InsertedExpressions[S] = (Value*)I;
InsertedInstructions.insert(I);
}
/// expandCodeFor - Insert code to directly compute the specified SCEV
/// expression into the program. The inserted code is inserted into the
/// specified block.
///
/// If a particular value sign is required, a type may be specified for the
/// result.
Value *expandCodeFor(SCEVHandle SH, Instruction *IP, const Type *Ty = 0) {
// Expand the code for this SCEV.
this->InsertPt = IP;
return expandInTy(SH, Ty);
}
protected:
Value *expand(SCEV *S) {
// Check to see if we already expanded this.
std::map<SCEVHandle, Value*>::iterator I = InsertedExpressions.find(S);
if (I != InsertedExpressions.end())
return I->second;
Value *V = visit(S);
InsertedExpressions[S] = V;
return V;
}
Value *expandInTy(SCEV *S, const Type *Ty) {
Value *V = expand(S);
if (Ty && V->getType() != Ty) {
// FIXME: keep track of the cast instruction.
if (Constant *C = dyn_cast<Constant>(V))
return ConstantExpr::getCast(C, Ty);
else if (Instruction *I = dyn_cast<Instruction>(V)) {
// Check to see if there is already a cast. If there is, use it.
for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
UI != E; ++UI) {
if ((*UI)->getType() == Ty)
if (CastInst *CI = dyn_cast<CastInst>(cast<Instruction>(*UI))) {
BasicBlock::iterator It = I; ++It;
if (isa<InvokeInst>(I))
It = cast<InvokeInst>(I)->getNormalDest()->begin();
while (isa<PHINode>(It)) ++It;
if (It != BasicBlock::iterator(CI)) {
// Splice the cast immediately after the operand in question.
BasicBlock::InstListType &InstList =
It->getParent()->getInstList();
InstList.splice(It, CI->getParent()->getInstList(), CI);
}
return CI;
}
}
BasicBlock::iterator IP = I; ++IP;
if (InvokeInst *II = dyn_cast<InvokeInst>(I))
IP = II->getNormalDest()->begin();
while (isa<PHINode>(IP)) ++IP;
return new CastInst(V, Ty, V->getName(), IP);
} else {
// FIXME: check to see if there is already a cast!
return new CastInst(V, Ty, V->getName(), InsertPt);
}
}
return V;
}
Value *visitConstant(SCEVConstant *S) {
return S->getValue();
}
Value *visitTruncateExpr(SCEVTruncateExpr *S) {
Value *V = expand(S->getOperand());
return new CastInst(V, S->getType(), "tmp.", InsertPt);
}
Value *visitZeroExtendExpr(SCEVZeroExtendExpr *S) {
Value *V = expandInTy(S->getOperand(),S->getType()->getUnsignedVersion());
return new CastInst(V, S->getType(), "tmp.", InsertPt);
}
Value *visitAddExpr(SCEVAddExpr *S) {
const Type *Ty = S->getType();
Value *V = expandInTy(S->getOperand(S->getNumOperands()-1), Ty);
// Emit a bunch of add instructions
for (int i = S->getNumOperands()-2; i >= 0; --i)
V = BinaryOperator::createAdd(V, expandInTy(S->getOperand(i), Ty),
"tmp.", InsertPt);
return V;
}
Value *visitMulExpr(SCEVMulExpr *S);
Value *visitUDivExpr(SCEVUDivExpr *S) {
const Type *Ty = S->getType();
Value *LHS = expandInTy(S->getLHS(), Ty);
Value *RHS = expandInTy(S->getRHS(), Ty);
return BinaryOperator::createDiv(LHS, RHS, "tmp.", InsertPt);
}
Value *visitAddRecExpr(SCEVAddRecExpr *S);
Value *visitUnknown(SCEVUnknown *S) {
return S->getValue();
}
};
}
Value *SCEVExpander::visitMulExpr(SCEVMulExpr *S) {
const Type *Ty = S->getType();
int FirstOp = 0; // Set if we should emit a subtract.
if (SCEVConstant *SC = dyn_cast<SCEVConstant>(S->getOperand(0)))
if (SC->getValue()->isAllOnesValue())
FirstOp = 1;
int i = S->getNumOperands()-2;
Value *V = expandInTy(S->getOperand(i+1), Ty);
// Emit a bunch of multiply instructions
for (; i >= FirstOp; --i)
V = BinaryOperator::createMul(V, expandInTy(S->getOperand(i), Ty),
"tmp.", InsertPt);
// -1 * ... ---> 0 - ...
if (FirstOp == 1)
V = BinaryOperator::createNeg(V, "tmp.", InsertPt);
return V;
}
Value *SCEVExpander::visitAddRecExpr(SCEVAddRecExpr *S) {
const Type *Ty = S->getType();
const Loop *L = S->getLoop();
// We cannot yet do fp recurrences, e.g. the xform of {X,+,F} --> X+{0,+,F}
assert(Ty->isIntegral() && "Cannot expand fp recurrences yet!");
// {X,+,F} --> X + {0,+,F}
if (!isa<SCEVConstant>(S->getStart()) ||
!cast<SCEVConstant>(S->getStart())->getValue()->isNullValue()) {
Value *Start = expandInTy(S->getStart(), Ty);
std::vector<SCEVHandle> NewOps(S->op_begin(), S->op_end());
NewOps[0] = SCEVUnknown::getIntegerSCEV(0, Ty);
Value *Rest = expandInTy(SCEVAddRecExpr::get(NewOps, L), Ty);
// FIXME: look for an existing add to use.
return BinaryOperator::createAdd(Rest, Start, "tmp.", InsertPt);
}
// {0,+,1} --> Insert a canonical induction variable into the loop!
if (S->getNumOperands() == 2 &&
S->getOperand(1) == SCEVUnknown::getIntegerSCEV(1, Ty)) {
// Create and insert the PHI node for the induction variable in the
// specified loop.
BasicBlock *Header = L->getHeader();
PHINode *PN = new PHINode(Ty, "indvar", Header->begin());
PN->addIncoming(Constant::getNullValue(Ty), L->getLoopPreheader());
pred_iterator HPI = pred_begin(Header);
assert(HPI != pred_end(Header) && "Loop with zero preds???");
if (!L->contains(*HPI)) ++HPI;
assert(HPI != pred_end(Header) && L->contains(*HPI) &&
"No backedge in loop?");
// Insert a unit add instruction right before the terminator corresponding
// to the back-edge.
Constant *One = Ty->isFloatingPoint() ? (Constant*)ConstantFP::get(Ty, 1.0)
: ConstantInt::get(Ty, 1);
Instruction *Add = BinaryOperator::createAdd(PN, One, "indvar.next",
(*HPI)->getTerminator());
pred_iterator PI = pred_begin(Header);
if (*PI == L->getLoopPreheader())
++PI;
PN->addIncoming(Add, *PI);
return PN;
}
// Get the canonical induction variable I for this loop.
Value *I = getOrInsertCanonicalInductionVariable(L, Ty);
if (S->getNumOperands() == 2) { // {0,+,F} --> i*F
Value *F = expandInTy(S->getOperand(1), Ty);
return BinaryOperator::createMul(I, F, "tmp.", InsertPt);
}
// If this is a chain of recurrences, turn it into a closed form, using the
// folders, then expandCodeFor the closed form. This allows the folders to
// simplify the expression without having to build a bunch of special code
// into this folder.
SCEVHandle IH = SCEVUnknown::get(I); // Get I as a "symbolic" SCEV.
SCEVHandle V = S->evaluateAtIteration(IH);
//std::cerr << "Evaluated: " << *this << "\n to: " << *V << "\n";
return expandInTy(V, Ty);
}
namespace {
Statistic<> NumRemoved ("indvars", "Number of aux indvars removed");
Statistic<> NumPointer ("indvars", "Number of pointer indvars promoted");